Seal composition

Abstract

The object of this invention is to provide a sealing composition that possesses the properties of crosslinked rubber while being detachable and reformable, and a method for producing the same. [Solution] The present invention provides a sealing composition containing a bond-exchange type dynamic covalent bond-containing rubber polymer, comprising: (I): a carboxyl group-modified rubber polymer (A) which is a carboxyl group-modified isoprene polymer (A1) and / or a carboxyl group-modified silicone polymer (A2); and (II): a compound (B) having two or more epoxy groups, wherein the connecting portion of the constituent units (I) and (II) includes a bond-exchange type dynamic covalent bond between the carboxyl group of the polymer (A) and the epoxy group of the compound (B).

Description

[Technical Field]

[0001] This disclosure relates to a sealing composition, and more particularly to a sealing composition containing a bond-exchange type dynamic covalent bond-containing rubber polymer and a method for producing the same. [Background technology]

[0002] Cross-linked rubber exhibits excellent properties characteristic of rubber, such as elasticity, due to its three-dimensional network structure in which polymer chains are linked. For this reason, it is used as a sealing material for O-rings, gaskets, etc. For example, natural rubber and isoprene rubber, which has a similar chemical structure, have high tensile strength and excellent abrasion resistance and vibration absorption, so they are used in various rubber products such as vibration damping rubber, tires, hoses, and belts.

[0003] For example, Patent Document 1 describes a sealing material formed by crosslinking an uncrosslinked rubber composition containing ethylene-α-olefin-diene rubber and a compound having a perfluoropolyether skeleton. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2024-124665 [Overview of the project] [Problems that the invention aims to solve]

[0005] The crosslinked rubber network structure described in Patent Document 1 is formed by strong covalent bonds, and the crosslinking points are irreversible and do not have self-healing properties. Therefore, once sealed, it is difficult to detach. Furthermore, in recent years, from the standpoint of environmental protection and resource conservation, the reuse of used materials is desired, but the aforementioned crosslinked rubber sealing material is difficult to regenerate.

[0006] This disclosure has been made in view of the above circumstances, and aims to provide a sealing composition that possesses the properties of crosslinked rubber and is detachable and reformable, as well as a method for manufacturing the same.

[0007] The present invention provides the following [1] to

[13] . [1] Constituent unit (I): A constituent unit derived from a carboxyl group-modified rubber polymer (A), which is a carboxyl group-modified isoprene polymer (A1) and / or a carboxyl group-modified silicone polymer (A2), Constituent unit (II): A constituent unit derived from compound (B) having two or more epoxy groups Includes, The connecting portion of the constituent units (I) and (II) includes a bond exchange type dynamic covalent bond between the carboxyl group of the polymer (A) and the epoxy group of the compound (B). A sealing composition containing a bond-exchange type dynamic covalent rubber polymer. [2] The composition according to [1], wherein the mass-average molecular weight of the isoprene polymer (A1) is 5,000 to 1,000,000,005,000. [3] The composition according to [1], wherein the number average molecular weight of the silicone polymer (A2) is 700 to 40,000. [4] The composition according to any one of [1] to [3], wherein the carboxyl group equivalent of the carboxyl group-modified rubber polymer (A) is 150 to 40,000 g / mol. [5] The composition according to any one of [1] to [4], wherein the compound (B) comprises one or more compounds (B1) selected from epoxy group-modified silicone oil, 1,4-butanediol diglycidyl ether, 1,2,7,8-diepoxyoctane, and neopentyl glycol diglycidyl ether. [6] The composition according to any one of [1] to [4], wherein the compound (B) further comprises a compound (B2) having a tertiary amine structure. [7] The composition according to [6], wherein the compound (B2) comprises one or more compounds selected from 4,4'-methylenebis(N,N-diglycidylaniline), N,N'-[1,3-phenylenebis(methylene)]bis[bis(oxiran-2-ylmethyl)amine], 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, and N-[2-methyl-4-(oxiranylmethoxy)phenyl]-N-(oxiranylmethoxy)oxiranimethaneamine). [8] The composition according to any one of [1] to [7], wherein the bond-exchange type dynamic covalent bond-containing rubber polymer further comprises a transesterification catalyst (C), which is a polymer obtained by crosslinking the polymer (A) and the compound (B) with a transesterification catalyst (C). [9] The composition according to [8], wherein the catalyst (C) comprises one or more selected from zinc acetate, zinc acetylacetone(II) salt, triphenylphosphine, and 1,5,7-triazabicyclo[4.4.0]deca-5-ene.

[10] The composition according to [8] or [9], wherein the polymer (A) at the time of crosslinking is liquid. A sealing material which is a molded article of any one of the compositions described in item

[11] , [1], to

[10] .

[12] A waterproof seal, as described in

[11] .

[13] Carboxyl group modified rubber polymer (A), which is a carboxyl group modified isoprene polymer (A1) and / or a carboxyl group modified silicone polymer (A2), Compound (B) having two or more epoxy groups, and Transesterification catalyst (C) A step of mixing to prepare a rubber composition, A step of heating the rubber composition to crosslink it and produce a bond-exchange type dynamic covalent bond-containing rubber polymer, and A step of forming the rubber polymer to construct a sealing material, A method for manufacturing a sealing material, including the method described above. [Effects of the Invention]

[0008] Since the sealing composition of the present invention contains a rubber polymer having dissociative-reassociative dynamic covalent bonds, dissociation and recombination of the bonds are possible, and it has elasticity which is a characteristic of rubber. Therefore, it can exhibit good adhesiveness and disassembly property as a sealing material. In addition, since re-adhesion and re-disassembly are possible after disassembly, reuse and recycling are easy, and it is useful as a sealing material considering the environment.

Embodiments for Carrying Out the Invention

[0009] In this specification, when described as "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, it includes the meaning of "X or more and Y or less", and also the meaning of "preferably larger than X" or "preferably smaller than Y".

[0010] In this specification, for numerical ranges described stepwise, unless otherwise specified, the upper limit value or lower limit value of a numerical range at a certain step can be arbitrarily combined with the upper limit value or lower limit value of a numerical range at another step. Also, in the numerical ranges described in this specification, the upper limit value or lower limit value of the numerical range can be replaced with the value shown in the examples.

[0011] In this specification, "X and / or Y" (X and Y are arbitrary components) means, unless otherwise specified, at least one of X and Y, and means three cases: only X, only Y, and X and Y.

[0012] 〔1. Rubber Polymer Containing Dissociative-Reassociative Dynamic Covalent Bonds〕 The sealing composition of the present invention contains a rubber polymer containing dissociative-reassociative dynamic covalent bonds. The rubber polymer containing dissociative-reassociative dynamic covalent bonds is a polymer containing structural units (I) and (II). Structural units (I) and (II) are structural units derived from the following raw materials, respectively.

[0013] 〔1.1 (A) Carboxyl Group-Modified Rubber Polymer〕 The structural unit (I) is a structural unit derived from a carboxyl group-modified rubber polymer (A) (hereinafter sometimes simply referred to as rubber polymer (A)). In this specification, the carboxyl group-modified rubber polymer is an unvulcanized rubber polymer having a carboxyl group.

[0014] -Carboxyl group- Examples of the carboxyl group include, for example, -COOH, -COO-, -COOR (R is a metal atom or an ammonium group), and any of them may be used. The content of the carboxyl group in the rubber polymer (A) is preferably 0.05 to 5% by mass, more preferably 0.1 to 3% by mass, and still more preferably 0.5 to 2% by mass based on the mass of the polymer (A). The position of the carboxyl group in the polymer (A) also varies depending on the type of the polymer (A), and it may be in the side chain, at the molecular end, or both, but it is preferably included at least in the side chain. For example, when the polymer (A) is polyisoprene (A1) having a carboxyl group, it is preferable that the carboxyl group is bonded to the carbon atom at the 4th position of the main chain of the isoprene monomer unit, and one or more (preferably one) hydrogen atoms bonded to the carbon atom are represented by the following formula: -R 1 -COOH. In the formula, R 1 is a divalent alkyl group (for example, a divalent alkyl group having 1 to 5 carbon atoms, preferably a methylene group), or -R 2 (COOR 3 )- (R 2 is a trivalent alkyl group having 1 to 5 carbon atoms, preferably -CH-, and R 3 represents a monovalent alkyl group having 1 to 5 carbon atoms, preferably a methyl group. When the polymer (B) is polysiloxane (A2) having a carboxyl group, it is preferable that the carboxyl group is bonded to the silicon atom of the siloxane monomer unit, and one or more (preferably one) hydrogen atoms bonded to the silicon atom are represented by the following formula: -R 4 -COOH. R 4 is a divalent alkyl group (for example, a divalent alkyl group having 1 to 5 carbon atoms, preferably a methylene group).

[0015] The carboxyl group equivalent of rubber polymer (A) is preferably 150 g / mol or more, more preferably 200 g / mol or more, and even more preferably 250 g / mol or more. The upper limit is preferably 40,000 g / mol or less, more preferably 300,000 or less, and even more preferably 20,000 g / mol or less. Therefore, 150 to 40,000 g / mol is preferred, 200 to 30,000 g / mol is more preferred, and 250 to 20,000 g / mol is even more preferred.

[0016] -Raw rubber polymer- The raw rubber polymers used as raw materials for the carboxyl group-modified rubber polymer (A) include various natural and synthetic rubbers such as polyisoprene, polysiloxane, hydrogenated polyisoprene, polybutadiene, styrene-butadiene copolymer, isobutylene-isoprene copolymer, ethylene-propylene copolymer, and ethylene-propylene-diene ternary copolymer. Of these, polyisoprene (isoprene polymer) and polysiloxane (silicone polymer) are preferred.

[0017] -Method for producing carboxyl group-modified rubber polymer- The method for producing the carboxyl group-modified rubber polymer (A) is not particularly limited, but examples include copolymerizing a monomer having a carboxyl group with a base polymer during the production of the raw rubber polymer, and graft polymerizing a monomer having a carboxyl group after the production of the rubber polymer.

[0018] -Physical properties of carboxyl group-modified rubber polymers- The mass-average molecular weight of the carboxyl group-modified rubber polymer (A) (for example, in the case of carboxyl group-modified isoprene polymer (A1)) is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 20,000 or more. The upper limit is preferably 1,000,000 or less, more preferably 900,000 or less, and even more preferably 800,000 or less. Therefore, it is preferably 5,000 to 1,000,000, more preferably 10,000 to 900,000, and even more preferably 20,000 to 800,000. The mass-average molecular weight can be measured as the mass-average molecular weight on a polystyrene basis by gel permeation chromatography (GPC).

[0019] The number-average molecular weight of the carboxyl group-modified rubber polymer (A) (for example, in the case of carboxyl group-modified silicone polymer (A2)) is preferably 700 or more, more preferably 900 or more, and even more preferably 1,000 or more. The upper limit is preferably 700,000 or less, more preferably 600,000 or less, and even more preferably 500,000 or less. Therefore, it is preferably 700 to 700,000, more preferably 900 to 600,000, and even more preferably 1,000 to 500,000. This improves the adhesion and decomposability of the resulting rubber polymer to the substrate and increases its flexibility.

[0020] The carboxyl group equivalent of the carboxyl group-modified isoprene polymer (A1) is preferably 700 to 40,000 g / mol, more preferably 1,000 to 30,000 g / mol, and even more preferably 2,000 to 20,000 g / mol. The carboxyl group equivalent of the carboxyl group-modified silicone polymer (A2) is preferably 150 to 10,000 g / mol, more preferably 200 to 8,000 g / mol, and even more preferably 250 to 5,000 g / mol. This allows the crosslinking reaction with compound (B) to proceed more rapidly.

[0021] The carboxyl group-modified rubber polymer (A) may be one type or a combination of two or more types, but preferably it includes a carboxyl group-modified isoprene polymer (A1) and / or a carboxyl group-modified silicone polymer (A2).

[0022] [1.2 (B) Compounds having two or more epoxy groups] The constituent unit (II) is a constituent unit derived from compound (B) (hereinafter sometimes simply referred to as compound (B)) which has two or more epoxy groups.

[0023] -Epoxy group- Compound (B) has epoxy groups. The number of epoxy groups in compound (B) is preferably two or more. The epoxy groups may be located at the molecular ends, side chains, or both, but it is more preferable that they be at the molecular ends, and even more preferable that they be at both ends.

[0024] Compound (B) may be a compound having a group containing an epoxy group. Examples of groups containing an epoxy group include a glycidyl group, an oxyranyl methoxy group, and a diglycidylamino group. Compound (B) only needs to have two or more epoxy groups or groups containing epoxy groups, and may have three or more, four or more, or more.

[0025] -Tertiary amine- Compound (B) may further contain a tertiary amine. This allows the tertiary amine to act as a base in the crosslinking reaction (ester bond formation by epoxy ring-opening reaction) between the carboxyl group of (A) and the epoxy group of (B), thereby promoting bonding. There should be one or more tertiary amines in the structure of the compound, and two or more are preferred. The tertiary amine is preferably included in the compound as a diglycidylamino group.

[0026] In this specification, among compounds (B), those having two or more epoxy groups and no tertiary amine are referred to as compound (B1), and those having two or more epoxy groups and a tertiary amine are referred to as compound (B2).

[0027] -Example of compound (B)- Compound (B) is preferably a compound that is compatible with component (A).

[0028] Examples of (B1) include compounds containing a structure in which two epoxy groups and / or epoxy-containing groups (e.g., a glycidyl group, an oxyranyl methoxy group) are linked by a divalent alkyl group. The divalent alkyl group may be linear, branched, or cyclic, and may contain saturated or unsaturated bonds, but linear or branched saturated alkyl groups are preferred. The number of carbon atoms in the alkyl group is preferably 1 to 8, more preferably 2 to 7, and even more preferably 3 to 6. Examples of (B1) include 1,4-butanediol diglycidyl ether, 1,2,7,8-diepoxyoctane, neopentyl glycol diglycidyl ether, and epoxy-modified rubber polymers. These can show good compatibility with (A). Among these, 1,4-butanediol diglycidyl ether and epoxy-modified rubber polymers (e.g., epoxy-modified silicone oil) are preferred. When component (A) is (A2), component (B) is preferably epoxy-modified silicone oil. This makes it possible to further enhance the flexibility of bond-exchange type dynamic covalent bond-containing rubber polymers.

[0029] Examples of compounds (B2) having two or more epoxy groups and a tertiary amine include compounds containing a structure in which two diglycidylamino groups are linked by a divalent alkyl group, and compounds containing a structure in which one end has a diglycidylamino group and the other end has an epoxy group, both linked by a divalent alkyl group. The alkyl group may be linear, branched, or cyclic, and may contain saturated or unsaturated bonds, but it is preferable that it contains one or more saturated or unsaturated carbon rings. The number of carbon atoms in the alkyl group is preferably 3 to 20, more preferably 4 to 18, and even more preferably 5 to 16, 5 to 14, or 5 to 13. Examples of (B2) include 4,4'-methylenebis(N,N-diglycidylaniline), N,N'-[1,3-phenylenebis(methylene)]bis[bis(oxiran-2-ylmethyl)amine], 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, and N-[2-methyl-4-(oxiranylmethoxy)phenyl]-N-(oxiranylmethoxy)oxiranimethaneamine. These can show good compatibility with (A). Among these, 4,4'-methylenebis(N,N-diglycidylaniline) is preferred.

[0030] Compound (B) may be one type or a combination of two or more types, and it is preferable that it contains at least compound (B1) and / or (B2). This allows the crosslinking reaction to proceed appropriately and enables the formation of a bond exchange type dynamic covalent bond.

[0031] [1.3 Bond exchange type dynamic covalent bond] The bond-exchange type dynamic covalent bond-containing rubber polymer contains constituent units derived from the rubber polymer (A) and compound (B) described above. The bond-exchange type dynamic covalent bond-containing rubber polymer is a polymer formed by an addition reaction (crosslinking reaction) between the carboxyl group of rubber polymer (A) and the epoxy group of compound (B). An example of the reaction in which rubber polymer (A) and compound (B2) bond, and the resulting bond-exchange type dynamic covalent bond-containing rubber polymer structure, is shown in the following formulas (1) and (2) (where * indicates a bond, Ar represents an alkyl group, and m, n, and l represent integers). [ka] [ka] A bond-exchange type dynamic covalent rubber polymer has covalent bonds (ester bonds) and hydroxyl groups, and the covalent bonds can form bond-exchange type dynamic covalent bonds (ordinary dynamic covalent bonds) within the polymer in the presence of hydroxyl groups. In this specification, a bond-exchange type dynamic covalent bond is a covalent bond (ester bond) that can simultaneously dissociate and recombine to other hydroxyl groups under external stimuli. An example of dissociation and recombination is shown in the following formulas (3) and (4) (the definition of substituents in the formulas is the same as in formulas (1) and (2)). [ka] [ka] Thus, complete dissociation does not occur during the reaction intermediate state, and new bonds can be formed without losing the connectivity of the polymer chains. As a result, it can be easily adhered to the sealing portion of the substrate, and peeling after use and repeated processes are possible. Furthermore, because it has self-healing properties, it has a long material life, making it easy to reuse and recycle, and thus useful as an environmentally friendly sealing material.

[0032] External stimuli include, for example, heating. The heating temperature can be set appropriately depending on the type of substrate, and is preferably 100°C or higher, preferably 110°C or higher, and more preferably 120°C or higher. The upper limit is preferably 200°C or lower, more preferably 190°C or lower, and even more preferably 180°C or lower. The heating time is, for example, 5 minutes or more, preferably 10 minutes or more, and more preferably 15 minutes or more.

[0033] The ratio of epoxy groups in compound (B) to carboxyl groups in rubber polymer (A) is preferably carboxyl groups:epoxy groups (equivalent ratio) = 1.0:0.5 to 1.0:2.0, more preferably 1.0:0.5 to 1.0:1.5. This allows the crosslinking reaction to proceed sufficiently and enables the formation of a suitable number of bond-exchange type covalent bonds. The hydroxyl group equivalent of compound (B) is preferably 50 or more, more preferably 60 or more, and even more preferably 70 or more. The upper limit is preferably 150 or less, more preferably 140 or less, and even more preferably 130 or less.

[0034] [1.4. Transesterification catalyst (C)] The composition preferably contains a transesterification catalyst (C) (hereinafter sometimes simply referred to as catalyst (C)). This makes it easier for the ester bonds in the bond-exchange type dynamic covalent-containing rubber polymer to function as bond-exchange type covalent bonds. In particular, when compound (B) is compound (B1), it is preferable to include catalyst (C). This can promote the transesterification reaction.

[0035] The transesterification catalyst (C) is not particularly limited as long as it is a catalyst such as an acid catalyst or metal catalyst involved in the bond exchange reaction, i.e., the transesterification reaction, in rubber polymers. Examples include zinc acetate, zinc acetylacetone(II) salt, triphenylphosphine, and 1,5,7-triazabicyclo[4.4.0]deca-5-ene. The transesterification catalyst may be used alone or in combination of two or more types.

[0036] The content of catalyst (C) is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, per 100 parts by mass of rubber polymer (A). This allows the catalyst to function well. The upper limit is preferably 10 parts by mass or less, more preferably 1 part by mass or less. This suppresses the influence on the properties of the bond-exchange type dynamic covalent bond-containing rubber polymer.

[0037] [2.Optional ingredients] The composition of the present invention may optionally contain other components. Examples of other components include a reinforcing agent (D) and a crosslinking reaction catalyst (E).

[0038] -Reinforcement material (D)- By incorporating a reinforcing material (D), the properties of the resulting composition, such as hardness, tensile strength, and elongation, can be improved. Examples of reinforcing materials include crosslinked rubbers such as silica, carbon, talc, and mica, with silica and carbon being preferred. Hydrophobic silica is preferred. In this specification, hydrophobic silica refers to silica whose surface has been subjected to a hydrophobic treatment. Hydrophobic silica can further improve the dispersibility of the rubber polymer (A). The reinforcing material may be used alone or in combination of two or more types. The content of the reinforcing material can be adjusted according to the desired properties of the rubber polymer; for example, 5 to 30 parts by mass and more than 10 to 25 parts by mass per 100 parts by mass of polymer (A) is preferred.

[0039] -Crosslinking reaction catalyst (E)- By using a crosslinking catalyst, the bonding between polymer (A) and compound (B), specifically the addition reaction (crosslinking reaction) between the carboxyl group of polymer (A) and the epoxy group of compound (B), can be accelerated, allowing for the production of rubber polymers in a shorter time. Examples of crosslinking catalysts include tertiary amines and imidazoles, which can be appropriately determined based on the types of polymer (A) and compound (B). One type of crosslinking catalyst may be used alone, or two or more types may be used in combination. The content of the crosslinking catalyst should be appropriately determined depending on the materials used, crosslinking conditions, etc. For example, 0.1 to 5 parts by mass, and more preferably 0.1 to 1 part by mass, is preferred per 100 parts by mass of polymer (A).

[0040] The composition of the present invention may contain components other than those described in (D) and (E) above. Examples include preservatives, antioxidants, surfactants, light stabilizers, colorants, and the like.

[0041] [3. Method for producing the composition] A method for producing the composition of the present invention includes, for example, a rubber polymer composition preparation step and a crosslinking step. This method allows for the simple production of a rubber polymer composition through relatively simple steps.

[0042] [3.1 Step (1): Rubber Polymer Composition Preparation Step] In step (1), the rubber polymer (A), compound (B), and any additional materials as needed are mixed together and stirred to prepare the rubber polymer composition. The order in which the materials are added is not particularly limited; they may be added all at once or sequentially. Stirring with shear force is preferred, and it is preferable to use a stirrer such as a blade stirrer.

[0043] When compounding each material, the rubber polymer (A) is preferably in liquid form. For example, in the case of (A1), side-chain carboxyl group-modified liquid polyisoprene is preferred, and in the case of (A2), carboxyl group-modified silicone oil is preferred. This makes it possible to increase the molecular weight of the resulting polymer.

[0044] As mentioned above, when compound (B1) is used, it is preferable to further use catalyst (C). When adding catalyst (C) and / or (E), which are used as needed, to the system, it is preferable to use a solvent. This makes it easier to mix with other materials even when using catalysts that are difficult to dissolve (e.g., in powder form). In this case, for example, the catalyst may be dissolved in a solvent to prepare a catalyst solution, and the remaining materials may be added to this. Examples of solvents include chloroform, methanol, ethanol, and a mixture of two or more solvents selected from these. The concentration of the catalyst in the catalyst solution is preferably 1.0 mg / mL or higher, more preferably 2.5 mg / mL or higher. This can increase production efficiency. The upper limit is preferably 20 mg / mL or less, and more preferably 10 mg / mL or less. This can avoid situations where the catalyst does not dissolve.

[0045] When preparing a rubber polymer composition using a catalyst solution, it is preferable to remove the solvent prior to the next step (2). This increases the heating efficiency in step (2) and allows the crosslinking reaction to proceed more effectively.

[0046] [3.2 Step (2): Crosslinking step] In step (2), the rubber polymer composition is heated to allow the crosslinking reaction to proceed. The heating temperature can be appropriately determined considering the type of material, physical properties such as melting point and softening point, productivity, etc., but for example, it is 120 to 150°C. In addition, a reduced pressure treatment may be performed during heating. This can accelerate the crosslinking reaction and shorten the crosslinking time.

[0047] [4. Sealant] The composition of the present invention can be used as a sealing material. That is, the composition of the present invention can be used as a sealing material by appropriately molding it. The molding method is not particularly limited, but examples include injection molding, extrusion molding (inflation method, T-die method), and vacuum forming. Equipment suitable for the molding method can be used during molding. The substrate to be used for the sealing material is preferably a substrate containing a material having ester groups or hydroxyl groups on its surface. This allows it to bond with the bond-exchange type dynamic covalent bonds of the rubber polymer and adhere to them. The hydroxyl groups and ester groups on the substrate surface can be introduced by surface treatment (e.g., plasma treatment, UV treatment, corona treatment). Examples of substrates include resin substrates such as nylon, polyimide, polyphenylene sulfide, and polyether ether ketone, and metal substrates such as stainless steel, aluminum, and iron. The applications of the substrate are not particularly limited and include various fields such as vehicles (automobiles, trains, aircraft, etc.), electrical and electronic components, medical equipment, household goods, and daily necessities and general merchandise.

[0048] When using the composition of the present invention as a sealing material, one method of bonding it to the substrate is, for example, to apply an external stimulus (e.g., heating) to the composition and then cool it while it is in contact with the sealing portion of the substrate. The sealing material can also be disassembled by heating it again. After disassembly, it can be used again as a sealing material for the same substrate or a different substrate.

[0049] The composition of the present invention can be used as a sealing material in various applications. Examples include O-rings, gaskets, and packings, and it can be used as a sealing material on both moving and stationary surfaces. The composition of the present invention can be bonded to the substrate surface using bond-exchange type dynamic covalent bonding. Furthermore, since it also possesses the elasticity characteristic of rubber, it can exhibit high adhesion regardless of the shape of the substrate surface, even without reinforcement such as screw fastening. Therefore, because it can fill gaps in the substrate or voids between substrates and provide a tight seal, it can be used as a sealing material for container sealing (adhesion between lids and containers) and waterproofing. [Examples]

[0050] Next, the present invention will be described in detail with reference to examples. However, the following examples represent only one aspect of the present invention, and the present invention is not limited thereto.

[0051] Example 1 An isoprene polymer composition was prepared by adding 100 parts by mass of side-chain carboxyl group-modified liquid polyisoprene (LIR-410, manufactured by Kuraray Co., Ltd., carboxyl group equivalent: 3,000 g / mol, mass-average molecular weight: 30,000) as the carboxyl group-modified isoprene rubber polymer (A1) and 3.5 parts by mass of 4,4'-methylenebis(N,N-diglycidylaniline) (hydroxyl group equivalent: 105.5) as (B2) to a planetary mixer and stirring for 15 minutes. Next, the prepared isoprene polymer composition was removed and crosslinked at a temperature of 150°C for 1 hour. The blending ratio of rubber polymer (A1) to compound (B2) was adjusted so that the equivalent ratio of carboxyl groups to epoxy groups was 1:1 (epoxy group amount / carboxyl group amount = 1).

[0052] Example 2 As the carboxyl group-modified silicone rubber polymer (A2), side-chain type carboxyl group-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., "X-22-3710E", number average molecular weight: 1,000, carboxyl group equivalent: 1450 g / mol) 100 parts by mass, and as the compound (B2), 4,4'-methylenebis(N,N-diglycidylaniline) 4.2 parts by mass, and as the reinforcing material (D), silica powder (hydrophobic fumed silica surface-treated with hexamethyldisilazane, manufactured by EVONIK, "AEROSIL (registered trademark) RX200", specific surface area 200 m 2 / g) 20 parts by mass were charged into a planetary mixer and stirred for 5 minutes to prepare a silicone composition. Next, the silicone composition was taken out and crosslinked under reduced pressure at a temperature of 120°C and about 2666 Pa for 4 hours. The blending amounts of the rubber polymer (A2) and the compound (B2) were adjusted so that the equivalent ratio of the carboxyl group to the epoxy group was 1:1 (epoxy group amount / carboxyl group amount = 1).

[0053] Comparative Example 1 100 parts by mass of natural rubber, 2.23 parts by mass of Sulfax T10, 3.5 parts by mass of Sanseler CZ-G, and 20 parts by mass of Show Black N330 were kneaded on a roll and crosslinked at a temperature of 150°C for 20 minutes to produce a sulfur-crosslinked isoprene polymer, which was used as it was.

[0054] Comparative Example 2 A two-component curable silicone rubber (Shin-Etsu Chemical Co., Ltd., KE-1950-40 A / B) was used as it was.

[0055] Comparative Example 3 A two-component curable epoxy-based adhesive (Three Bond Co., Ltd., TB2082C) was used as it was.

[0056] [Evaluation Method] -Adhesiveness- Samples of the examples and comparative examples (length x width x thickness = 10cm x 10cm x 0.1cm) were sandwiched between substrates (66 nylon (PA66), size length x width x thickness = 10cm x 10cm x 0.1cm) that had undergone surface treatment (plasma treatment or UV treatment), and bonded at 150°C for 20 minutes. The bonded samples were evaluated according to the following criteria. ○: Tensile shear test was conducted, and the peel force was 0.1 MPa or greater. ×: Not glued at all

[0057] -Disassembly- In evaluating adhesion, a peel test was performed after the bonding treatment while reheating at 150°C for 20 minutes, and the results were evaluated according to the following criteria. ○: Peelable ×: Not removable

[0058] [Table 1]

[0059] Comparative Examples 1-3, which lacked the bond-exchange type dynamic covalent bond, either showed no adhesion or exhibited poor decomposition properties even if adhesion was present. Furthermore, Comparative Example 3 exhibited dripping. In contrast, Examples 1 and 2, which possessed the bond, showed excellent adhesion and decomposition properties. These results indicate that the sealing composition of the present invention is a sealing material that is detachable from the substrate and is also environmentally friendly. [Industrial applicability]

[0060] The sealing composition of the present invention can be used as a sealing material in various products, such as those for automobiles and other vehicles.

Claims

1. Constituent unit (I): A constituent unit derived from a carboxyl group-modified rubber polymer (A), which is a carboxyl group-modified isoprene polymer (A1) and / or a carboxyl group-modified silicone polymer (A2), Constituent unit (II): A constituent unit derived from a compound (B) having two or more epoxy groups Includes, The connecting portion of the constituent units (I) and (II) includes a bond exchange type dynamic covalent bond between the carboxyl group of the polymer (A) and the epoxy group of the compound (B). A sealing composition containing a bond-exchange type dynamic covalent rubber polymer.

2. The composition according to claim 1, wherein the mass-average molecular weight of the isoprene polymer (A1) is 5,000 to 1,000,000.

3. The composition according to claim 1, wherein the number average molecular weight of the silicone polymer (A2) is 700 to 40,000.

4. The composition according to any one of claims 1 to 3, wherein the carboxyl group equivalent of the carboxyl group-modified rubber polymer (A) is 150 to 40,000 g / mol.

5. The composition according to claim 1 or 2, wherein the compound (B) comprises one or more compounds (B1) selected from epoxy group-modified silicone oil, 1,4-butanediol diglycidyl ether, 1,2,7,8-diepoxyoctane, and neopentyl glycol diglycidyl ether.

6. The composition according to claim 1 or 2, wherein the compound (B) further comprises a compound (B2) having a tertiary amine structure.

7. The composition according to claim 6, wherein the compound (B2) comprises one or more compounds selected from 4,4'-methylenebis(N,N-diglycidylaniline), N,N'-[1,3-phenylenebis(methylene)]bis[bis(oxiran-2-ylmethyl)amine], 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, and N-[2-methyl-4-(oxiranylmethoxy)phenyl]-N-(oxiranylmethoxy)oxiranimethaneamine).

8. The composition according to claim 1 or 2, wherein the bond-exchange type dynamic covalent bond-containing rubber polymer is a polymer obtained by crosslinking the polymer (A) and the compound (B) with a transesterification catalyst (C).

9. The composition according to claim 8, wherein the catalyst (C) comprises one or more selected from zinc acetate, zinc acetylacetone(II) salt, triphenylphosphine, and 1,5,7-triazabicyclo[4.4.0]deca-5-ene.

10. The composition according to claim 8, wherein the polymer (A) is liquid when crosslinked.

11. A sealing material which is a molded article of the composition according to claim 1 or 2.

12. The sealing material according to claim 11, which is a waterproof seal.

13. Carboxyl group-modified rubber polymer (A), which is a carboxyl group-modified isoprene polymer (A1) and / or a carboxyl group-modified silicone polymer (A2), Compound (B) having two or more epoxy groups, and Transesterification catalyst (C) A step of mixing to prepare a rubber composition, A step of heating the rubber composition to crosslink it and produce a bond-exchange type dynamic covalent bond-containing rubber polymer, and A step of forming the rubber polymer to construct a sealing material, A method for manufacturing a sealing material, including the method described above.

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